Same here across:
5 customers, 12 SEPMs (12.1 RU2,RU3 and RU4).
I also point out that our 11.x SEPMs (yes we're still fighting to get these upgraded) are perfectly fine and show the latest manager version correctly.
We report to our customers on a daily basis using the homepage monitors and as such will report to our customers the above quote from Mick2009:
"Treat that as a temporary cosmetic issue."
Will be monitoring this thread, since the last temporary cosmetic issue, turned out to require modification of the Server.xml or an upgrade to a 12.1.x.